Low blood pressure, or hypotension, is generally defined as a reading below 90/60 mmHg. While some people have chronically low blood pressure without symptoms, for others, it signals an underlying issue. There is no scientific evidence that low blood pressure directly causes weight gain. The relationship is a strong correlation driven by indirect factors that influence energy balance.
The Role of Fatigue and Reduced Activity
Common symptoms of hypotension, such as lightheadedness, dizziness, and chronic fatigue, significantly diminish a person’s overall energy levels. This persistent low energy directly impacts the amount of physical movement performed daily. The reduction in movement affects Non-Exercise Activity Thermogenesis (NEAT). NEAT includes all calories burned outside of structured exercise, such as walking, standing, and fidgeting. When fatigue causes a person to sit more and move less, their daily NEAT expenditure drops substantially. If caloric intake remains constant while energy expenditure decreases, the resulting positive energy balance leads to weight gain.
Shared Underlying Health Conditions
Low blood pressure and weight gain are frequently observed together because they can both be symptoms of a single, primary systemic health issue. Identifying the root cause requires looking beyond the blood pressure reading itself.
Hypothyroidism
An underactive thyroid gland, or hypothyroidism, slows the body’s metabolic rate, causing calories to be burned less efficiently and contributing to weight gain. Hypothyroidism can also cause hypotension by reducing the heart rate and the total volume of blood the heart pumps, known as cardiac output.
Adrenal Insufficiency
Adrenal insufficiency, such as Addison’s disease, occurs when the adrenal glands fail to produce adequate amounts of hormones like cortisol and aldosterone. Aldosterone is responsible for maintaining the balance of salt and water, and its deficiency leads to fluid loss, resulting in low blood pressure. This hormonal imbalance disrupts metabolism and energy regulation, often leading to unpredictable weight changes and fluid retention.
Nutritional Deficiencies
Deficiencies in certain micronutrients, such as iron or B vitamins, can contribute to chronic fatigue and anemia. These conditions may cause hypotension and subsequently impact energy expenditure and weight management.
Medications That Affect Both Systems
In some cases, weight gain is not a consequence of the low blood pressure or the underlying disease, but rather a side effect of the treatment itself. This is known as iatrogenic weight gain, meaning it is induced by medical intervention. Certain medications prescribed for conditions that coexist with chronic fatigue and low energy states are known to cause weight gain. Specific classes of antidepressants or anti-anxiety medications, often prescribed to manage the emotional toll of chronic illness, can stimulate appetite or alter metabolism. Medications managing hormonal imbalances also factor into weight changes. While thyroid hormone replacement generally helps stabilize weight, the precise dosage must be carefully monitored. Additionally, corticosteroid medications used to treat adrenal insufficiency often lead to weight gain due to increased fluid retention and appetite stimulation.
When to Talk to a Healthcare Provider
Any instance of unexplained or persistent low blood pressure combined with noticeable weight gain warrants a consultation with a healthcare provider. Professional guidance is important to determine if the two symptoms are linked by an underlying condition. A provider can conduct a thorough diagnostic workup, including blood tests, to rule out systemic diseases such as adrenal or thyroid disorders. Evaluation is particularly important if low blood pressure is accompanied by concerning symptoms, including chronic dizziness, recurrent fainting, or debilitating fatigue.